Movies often span years or decades of a character's life, which is usually achieved by casting multiple actors to play the different ages, or the use of prosthetics or CGI to make an actor appear older, even elderly, or younger. (Think Benjamin Button.)

But if a movie spans 12 years, it needs to be shot within a few months, right?

Not necessarily. Take "Boyhood," the extraordinarily well-reviewed film by Richard Linklater that is going into wider release. Taking risks is nothing new for this innovative filmmaker: he handed off "Slacker" to a different character in every scene, used rotoscoping animation techniques for "A Scanner Darkly" and "Waking Life;" and followed the relationship of Ethan Hawke and Julie Delpy over 20 years in the three films that comprise the "Before" trilogy. But with "Boyhood" he crosses another cinematic threshold, which follows the life of a Texas boy named Mason, played by Ellar Coltrane, from the age of six to eighteen. Linklater began filming this movie in 2002 when actor Coltrane was six years old. Every year he would film more scenes until Ellar was 18. "Boyhood" took 12 years to film.

A brave producer

But even with Linklater's track record, it would take a dedicated producer willing to wait that long to see a finished film. "'Wait, you start making a movie and we don't get our money back for 12 years?'" Linklater joked in a recent press junket. "Only the bravest guy imaginable who would agree to finance such a crazy thing like that, but Jonathan Sehring at IFC stuck with this film all the way."

Others weren't as adventurous. "I did talk to some producers I was working with and they were just like, 'No, I don't know how to, you can't, that's just crazy,'" Linklater recalled. "I'd done a couple films at IFC at that time. We had just finished 'Waking Life 'and 'Tape' and it was like, 'Yeah, okay, that could work.' But every day Jonathan had to jump through hoops at the corporate level, (with questions like) 'like what the hell is this?' "

Little doubt it was hard to sell, because not only of the manner it was filmed, but also because the overarching scope of its story.

"We're a very low budget, down and dirty film and yet it's kind of still epic in its scope," Linkater said.

Very wierd

"Tape" and "Waking Life" were Linklater's 2001 films. Prior to those, he had explored teenage and young adult life in films like "Dazed and Confused," "Before Sunrise" and "subUrbia." It was time for him to think about earlier childhood.

"I wanted to do something about childhood, but when I really sat down to write it, I couldn't pick one moment of childhood," Linklater said. "Obviously, with the limitations of film, you pick your moment." (He mentioned Truffaut's "The 400 Blows" as an example.) But I didn't have enough to say about one moment, so I just got this 'Eureka' moment of why couldn't you just film a little bit and encompass all of it? That was the idea that just hit me. It's so simple, actually, in a storytelling way, but the practicality of how you make a movie like that, that becomes the difficult part."

Writing a screenplay for a 12 years shoot was uncharted territory as well. "I'd say the whole structure was worked out pretty much," Linklater said. "I think by the second year I knew the last shot of the movie, but every year we would get together at we would just work on the various stages of the script. We had a year to think about it; (then) usually there was a very intensive three or four day shoot. I think at the end of the day we shot for 39 days total and we had 143 scenes. It was very weird. Everything about this film was weird."

A challenge

His story begins in 2002 just as the Iraqi war is beginning. Mason lives with Olivia, his recently divorced mom (Patricia Arquette) and his older sister (Lorelei Linklater, Richard's daughter). Mason's dad (for whom he is named) is played by Linklater regular Ethan Hawke. At the start Mason Sr. is in Alaska, finding himself; now he's back in Texas seeking to reconcile with Olivia. She, however, isn't interested; instead has enrolled in college and marries one of her professors. From there Mason moves from home-to-home, city-to-city (all in Texas), and grows from an inquisitive child to a gawky middle-schooler to a hipster high schooler over the film's nearly three-hour running time.

Coltrane is the film's discovery, At six, he was new to acting, but as the years went on, the filmmaking process became more integrated into his life.

"I think early on it was more of a challenge," Coltrane said. "Later on the characters started to merge in more with my actual life and it became much easier."

Adjusting the script

His experience, like the film is unique: no child actor has had the experience of revisiting the same character in the same film for 12 years.

"I want to say around 12 or 13 it began to gradually dawn on me what was actually happening," Coltrane said. "There was a certain point that I specifically remember where I just started to grasp the scope of the project."

As Coltrane grew up, Linklater adjusted the script for him, which he was prepared to do from the beginning. "] I felt I had a contour for the movie (that) it was always going to eventually go where these characters [went]," Linklater said. "I just knew if he grew up to be a wrestler, maybe that would've worked its way in. At some point, I don't know what year, the early inception of the character started morphing with whom he really is, to some degree."

12 years in the making

Spanning the last 12 years, "Boyhood" encompasses the Afghanistan and Iraq Wars, the Harry Potter sequels and other significant events of the decade. Those are signposts to tell you what year you're in as the film moves through time organically.

"The transitions were pretty important, what would get us from one year to the next and those changed over time," Linklater said. "In the early years I had more abrupt transitions that were kind of clever, but I ended up cutting out some of those to keep it less noticeable. I kind of discovered that a couple years in. It was always conceived like you would any sequence: It ends here, what's the next shot? And even though a year or more has elapsed, you're still going for a seamless flow within the narrative. But it somehow connects."

The dozen years also chronicled the decline of 35mm film as a cinema format. Linklater had already experimented with digital in "Tape," but chose to film "Boyhood" in a traditional manner. But by the time the film wrapped, he could tell film was on its way out.

"We started this in '02 and I thought, 'We're going to shoot 35mm negative because I think it will still be around 12 years from now,'" Linklater recalled. "But I swear to God, when we shot (towards the end) it felt like the equipment was bad, and the labs were not as good as they used to be just because there's less and less of it. But it was still very special to hear, 'Checking the gate' and getting lab reports. It felt like it was the end of that era. But I didn't want to shoot hi-def because I knew we would be on our fifth or sixth generation of whatever the best camera was, so the goal was to have it look like one movie with no technological difference (from beginning to end)."

The "Untitled 12 Year Project"

By the time it was all over, Coltrane had to process not only the end of his first film, but also the end of a lifelong endeavor. "[It was] bittersweet, for everyone on the crew," Coltrane said. "I was feeling this great relief and sadness at the same time. When it came to the end, I kind of discovered that every single person on the crew felt the same way. It was incredible. It's something that we all shared together. The last moment was difficult."

If you'd look up Linklater's filmography over the past 12 years, or at least the latter half, you might have seen "Boyhood" listed as the "Untitled 12 Year Project." The name "Boyhood" was actually one of the first things Linklater thought of.

"I think that name ended up on our call sheet," Linklater said. "That just became the title. We played with other titles but that one sort of, I don't know. When it comes to the title, good titles come early or not at all, so that was our title for better or worse."